package avicit.bdp.dds.dao.upgrade;

import avicit.bdp.dds.common.utils.ConnectionUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * mysql upgrade dao
 */
public class MysqlUpgradeDao extends UpgradeDao {

    public static final Logger logger = LoggerFactory.getLogger(MysqlUpgradeDao.class);

    /**
     * mysql upgrade dao holder
     */
    private static class MysqlUpgradeDaoHolder {
        private static final MysqlUpgradeDao INSTANCE = new MysqlUpgradeDao();
    }

    /**
     * mysql upgrade dao constructor
     */
    private MysqlUpgradeDao() {
    }

    public static final MysqlUpgradeDao getInstance() {
        return MysqlUpgradeDaoHolder.INSTANCE;
    }


    /**
     * determines whether a table exists
     * @param tableName tableName
     * @return if table exist return true，else return false
     */
    @Override
    public boolean isExistsTable(String tableName) {
        ResultSet rs = null;
        Connection conn = null;
        try {
            conn = dataSource.getConnection();
            rs = conn.getMetaData().getTables(null, null, tableName, null);
            return rs.next();
        } catch (SQLException e) {
            logger.error(e.getMessage(),e);
            throw new RuntimeException(e.getMessage(),e);
        } finally {
            ConnectionUtils.releaseResource(rs, conn);
        }

    }

    /**
     * determines whether a field exists in the specified table
     * @param tableName tableName
     * @param columnName columnName
     * @return  if column name exist return true，else return false
     */
    @Override
    public boolean isExistsColumn(String tableName,String columnName) {
        Connection conn = null;
        try {
            conn = dataSource.getConnection();
            ResultSet rs = conn.getMetaData().getColumns(null,null,tableName,columnName);
            return rs.next();

        } catch (SQLException e) {
            logger.error(e.getMessage(),e);
            throw new RuntimeException(e.getMessage(),e);
        } finally {
            ConnectionUtils.releaseResource(conn);
        }

    }

}
